diff --git a/fruitjam-build.sh b/fruitjam-build.sh
new file mode 100755
index 0000000..6bb594c
--- /dev/null
+++ b/fruitjam-build.sh
@@ -0,0 +1,58 @@
+#!/bin/sh
+set -e
+
+# Some configurations that actually work at the time I committed this:
+# ./fruitjam-build.sh  -v         # vga resolution, no psram, 128KiB
+# ./fruitjam-build.sh  -v -m448   # vga resolution, no psram,  448KiB
+# ./fruitjam-build.sh  -m4096     # 512x342 resolution, psram, 4096KiB
+
+DISP_WIDTH=512
+DISP_HEIGHT=342
+MEMSIZE=128
+CMAKE_ARGS=
+
+while getopts "hvm:" o; do
+    case "$o" in
+    (v)
+        DISP_WIDTH=640
+        DISP_HEIGHT=480
+        CMAKE_ARGS="$CMAKE_ARGS -DUSE_VGA_RES=1 -DHSTX_CKP=12 -DHSTX_D0P=14 -DHSTX_D1P=16 -DHSTX_D2P=18"
+        ;;
+    (m)
+        MEMSIZE=$OPTARG
+        ;;
+    (h|?)
+        echo "Usage: $0 [-v] [-m KiB]"
+        echo ""
+        echo "   -v: Use framebuffer resolution 640x480 instead of 512x342"
+        echo "   -m: Set memory size in KiB"
+        echo ""
+        echo "PSRAM is automatically set depending on memory & framebuffer details"
+        exit
+        ;;
+    esac
+done
+
+TAG=fruitjam_${DISP_WIDTH}x${DISP_HEIGHT}_${MEMSIZE}k
+PSRAM=$((MEMSIZE > 448 || DISP_WIDTH != 640))
+if [ $PSRAM -ne 0 ] ; then
+    TAG=${TAG}_psram
+    CMAKE_ARGS="$CMAKE_ARGS -DUSE_PSRAM=1"
+fi
+
+set -x
+make -C external/umac clean
+make -C external/umac DISP_WIDTH=${DISP_WIDTH} DISP_HEIGHT=${DISP_HEIGHT} MEMSIZE=${MEMSIZE}
+rm -f rom.bin
+./external/umac/main -r '4D1F8172 - MacPlus v3.ROM' -W rom.bin || true
+[ -f rom.bin ]
+xxd -i < rom.bin > incbin/umac-rom.h
+rm -rf build_${TAG}
+cmake -S . -B build_${TAG} \
+    -DPICO_SDK_PATH=../pico-sdk \
+    -DBOARD=adafruit_fruit_jam -DPICO_BOARD=pico2 \
+    -DMEMSIZE=${MEMSIZE} \
+    -DUSE_HSTX=1 \
+    -DSD_TX=35 -DSD_RX=36 -DSD_SCK=34 -DSD_CS=39 -DUSE_SD=1 \
+    ${CMAKE_ARGS}
+make -C build_${TAG} -j$(nproc)